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Drug-resistant malaria poised to cross into India

By Debora MacKenzie

Drug resistance is spreading, but we have the tools to keep tabs on it

(Image: Oxford Scientific/Getty)

Resistance to a vital drug against malaria has spread across Burma, reaching the Indian border. Unless contained, it could spread into India, then Africa, which has 90 per cent of the world’s malaria cases.

In the 1970s, resistance to classic antimalarial drugs such as chloroquine appeared in South-East Asia, and spread through Burma to India, then to Africa, where it trebled malaria deaths, killing 1.6 million people in 2004. That has been partly beaten back by a new class of drugs, artemisinins.

Resistance to artemisinins first appeared in Cambodia in 2007, then reached southern Burma. Resistant malaria parasites have mutations in a gene called K13. Now the mutant genes have been found in the blood of people with malaria in northern and eastern Burma. In fact, the genes showed up in more than a fifth of samples from seven of Burma’s 10 provinces – and in nearly half the samples from a clinic only 25 kilometres from the border with India.

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“The main threat is the spread of artemisinin resistance from Burma to India,” says Didier Menard of the Pasteur Institute in Phnom Penh, Cambodia. Because of widespread infection and the sheer size of the population, the burden of malaria in India is huge. Recent studies suggest there is little resistance there so far – but, says Menard, a study like the one in Burma needs to be done as soon as possible.

Mapping resistance

As well as genetically analysing blood samples, the researchers who carried out the study used geographical models to estimate the prevalence of resistance in areas where no samples were available. The resulting map shows where efforts to contain the spread of resistant malaria should be targeted. “Just getting people to complete the normal three-day treatment would certainly slow it down,” says team member Charles Woodrow of Mahidol University in Bangkok, Thailand.

Longer treatment or the use of a wider selection of drugs might also help, but Woodrow is pessimistic. Burma spends &dollar;20 per person a year on healthcare, the sixth-lowest outlay in the world.

Still, being able to track resistance by following the spread of mutant K13 genes means we can stop it. We need to avoid the situation in Cambodia, says Menard, where the once-potent combination of artemisinin with a second antimalarial is now failing in more than 40 per cent of cases. He says researchers in Burma should now designate a central laboratory to collect and standardise tests for resistance, map it as it emerges and lead the fight to contain it.